Method of manufacturing rubber chloride



Patented Mar. 2, 19s? UNITED STATES METHOD OF MANUFACTURING RUBBER CHLORIDE Erich Gebauer-Fuelnegg, deceased, late of Evanston, 111., by Marie Gebauer-Fuelnegg, Evanston, 111.,

administratrix, and Eugene W.

Moifett, Gary, Ind., assignors, by mesne assignments, to Marbo Patents, Inc., a corppration of Delaware No Drawing.

3 Claims.

This invention relates to a method of manufacturing rubber chloride and other halides of rubber or the main chemical constituents of rubber, such as polymers and derivatives of buta- 5 diene.

It has heretofore been known that rubber and similar compounds can be chlorinated by subjecting such compounds to the action of chlorine It is therefore an object of this invention to.

provide a halide of a-polymer or other derivative of a butadiene or diolefine.

Itis a more particularobject of this inven- 5 tion to provide a method of preparing rubber chloride by the use of liquefied chlorine. It is a further important object of this invention to provide a relatively simple and inexpensive method of preparing rubber chloride with 30 out the use of organic solvents by treatment of rubber with liquefied chlorine.

Other and further important objects of this invention will become apparent from the following description and appended claims.

Rubber and rubber-like substances as referred to in this specification includesubstances having the following nuclear formula:

in which R may be a suitable substituent group, such as for example an alkyl, aryl, halogen atom, hydrogen atom, and the like. This is a general nuclear formula for a group of polymerized hydrocarbons which may be derived from butadiene or erythrene. Members of this group of substances, generically referred to as polymerized butadiene bodies, are operative in the present process. The principal active ingredients of naturally occurring materials, such as rubber, gutta percha, balata, etc. belong to this group of hydrocarbons. These naturally occurring substances are the preferred starting materials in the com- 55 mercial operation of the present. process. How- Application January 28, 1935, Serial No. 3,804

even-it will be understood that butadiene, isoprene'and similar substances produced by artificial means are also operative. In fact, diolefines of the general formula CnH2n--2 and their polymers are operative for the purposes of my invention.

As an example of our process, as applied to a solid butadiene derivative, the following procedure is given:

Unvulcanized or partly vulcanized rubber is sheeted on suitable rolls to give a continuous strip, as described in the copending application of Gebauer-Fuelnegg, Molfett and Irving, Serial No. 739,554, filed August 13, 1934. The continuous strip of rubber is passed through a bath of liquefied chlorine at a rate sufficient to permit the reaction to run to the desired degree of completion. In the case of a strip of rubber having a thickness of less than about 0.02 of an inch, the time of immersion of the rubber in the liquid chlorine need not be more than several minutes but with thicker rubber sheets or strip material, thetime of immersion should be. increased somewhat, say, up to 4 to 6 minutes for rubber having a thickness of between 0.02 and 0.06 inch in thickness. After leaving the bath of liquid chlorine, the reacted rubber can be passed through a heated chamber to drive off any excess of chlorine or hydrogen chloride, which is formed as a byproduct of the reaction between rubber and chlorine.

Any rubber, either milled or unmilled, is suitable, although pale crepe rubber is preferred to smoked rubber, because of the lighter color of pale crepe rubber; Instead of forming the rubber into a strip of thin sheet material, the rubber may be subdivided in any manner desired so long as a relatively large surface area is presented to the chlorine. Powdered rubber may be used satisfactorily.

Milling the rubber has no effect upon the reaction but has the effect of increasing the plasticity of the finished sheet material, if the rubber chloride is to be made up into sheets or films. Consequently, where a harder sheet is desired, unmilled rubbershould be used. The use of milled rubber, however, has the additional advantage that the resulting rubber chloride is more readily soluble in the solvents used in preparing the sheet material than when unmilled rubber is used. Pale crepe rubber milled to a Williams plasticity of 210 and dead milled rubber having a Williams plasticity of 120 have been success fully used in this process. By dead milled rubber is meant rubber which has been milled until further milling will produce no further change in plasticity.

The reaction of the liquid chlorine on the rub ber results in a substantially completechlorination of the rubber if the nine of contact with the liquid chlorine is sufficient and if the partially reacted rubber is exposed to either natural or artificially produced ultraviolet light. Where the reaction is carried out wholly in the dark, the rubber absorbs the theoretical amount of chlorine to saturate the double bonds. The product corresponds mainly with the addition product, C5H8C12, and analyzes from 51 to 56% chlorine.

If, however, the rubber is exposed to light containing ultraviolet rays, after removal of the rubber from the liquid chlorine, a substitution reaction takes place, whereby the chlorine content is further increased to from to Exposure to light during immersion produces but little change in the chlorine content. Subsequent exposure to light, however, brings about the substitution of chlorine in the rubber molecule and thus aids in removing occluded chlorine from the final product.

Catalytic amounts, such as I by weight and I less, of such inorganic chemicals as phosphorus oxychloride, phosphorus pentachloride, selenium oxychloride and thionyl chloride, serve to effect a more complete reaction between the rubber and liquefied chlorine.

The hydrogen chloride that is given cfi during the addition reaction may be utilized in the hy drochlorination of rubber in accordance with the method disclosed in our Patent No. 1,980,396, dated November 13, 1934.

In carrying out the process of our invention,

it is preferable to have the rubber as dry as pos- 'or by the use of dehydrating chemicals, such as calcium chloride and the like.

As previously stated, the reaction between chlorine and rubber is carried out at a temperature at or below the boiling point of chlorine, which is --33.6 C. under atmospheric pressure. It is, however,, possible to maintain the chlorine in liquid condition by the use of elevated pressures even at slightly higher temperatures than the boiling point of chlorine, in accordance with the well known gas laws.

The process of this invention has the great advantage over other processes using gaseous chlorine in that it requires a matter of only minutes in which to carry the reaction to completion and the reaction can be carried out continuously by the use of sheet or strip rubber rather than as a batch process. In this way considerable economy in time and labor are made possible.

The rubber chloride, as obtained in our process, is a. whitish, spongy product of asbestos-like structure. When the rubber is reacted upon in sheet form, the product is directly obtained as a continuous sheet, greatly expanded as compared with the initial rubber sheet.

We are aware that numerous details of the process may be varied through a wide range without departing from the principles of this invention, and we, therefore, do not purpose limiting the patent granted hereon otherwise than necessitated by the prior art.

We claim as our invention:

1. In a process for producing a compound of a polymerized butadiene body and chlorine, the step of reacting the polymerized butadiene body with liquid chlorine at a temperature not above ---33.6 C.

2. In a process for producing a compound of rubber and chlorine, the step of reacting rubber with liquid chlorine at a temperature not above 33.6 C.

3. In a process for producing a compound of rubber and chlorine, the step of continuously;

passing thin sheet rubber through a bath of liquid chlorine at a temperature not substantially above -33.6 C. I 

